Power save for volte during silence periods

ABSTRACT

Methods and apparatus for reducing power consumption in a wireless device operating in a discontinuous transmission (DTX) mode while using a voice over Long Term Evolution (VoLTE) service. The wireless device detects a period of voice inactivity and transmits one or more silence descriptor (SID_UPDATE) frames to a second wireless device in place of encoded speech frames. The SID_UPDATE frames are transmitted periodically based on measurements of comfort noise parameters. The wireless device determines a difference between weighted averages of comfort noise (CN) parameters of two sequences of encoded speech frames. When the difference exceeds a difference threshold, a SID_UPDATE frame is transmitted. Additionally, in some embodiments, a SID_UPDATE frame is transmitted when the weighted average of CN parameters exceeds a parameter threshold and/or when a time between SID_UPDATE frames or time elapsed after entering a silence state exceeds one or more time thresholds.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional PatentApplication No. 62/005,881, filed May 30, 2014, and entitled “POWER SAVEFOR VOLTE DURING SILENCE PERIODS,” which is incorporated by referenceherein in its entirety for all purposes.

FIELD

The described embodiments generally relate to reducing power consumptionin wireless user equipment (UE), and more particularly, to methods andapparatus for power saving while using a voice over Long Term Evolution(VoLTE) service and operating in a discontinuous transmission (DTX)mode.

BACKGROUND

Battery life is a significant concern for UEs such as smartphones.Broadband radios, large touch screen displays and gigahertz multi-coreprocessors consume a substantial amount of energy. Therefore, poweroptimization that improves battery life is important to both mobilenetwork operators and smartphone manufacturers. The main componentsaffecting power consumption during voice calls are cellular radiotransmitters and receivers including voice codec components. Usually theUE's display is turned off by a trigger from either a proximity sensoror a timer.

Energy saving for cellular radio transmission and reception in the UEcan be achieved by turning off transmission and/or reception wheneverpossible. With the introduction of IP networks, voice over IP (VoIP)systems have been introduced. One implementation of a VoIP systemincludes a voice over Long Term Evolution (VoLTE) system. In VoLTEsystems, one mechanism to manage the operation of transmitters andreceivers of the UE is Discontinuous Transmission (DTX) andDiscontinuous Reception (DRX). A DTX mechanism uses a silence descriptor(SID) frame to minimize power consumption by the UE when there is aperiod of voice inactivity. Rather than send “silent” frames, the UE cansend a SID frame periodically, e.g., every eight frames, during theperiod of voice inactivity to reduce transmissions and to reduce powerconsumption of the UE. While the SID mechanism provides an improvementin power performance, it is desirable to develop apparatuses and methodsthat can further optimize power consumption at the UE, e.g., by managingadaptively the generation and transmission of SID frames.

SUMMARY

Power consumption is a challenge for user equipment (UE) when providinga voice over Long Term Evolution (VoLTE) service. One method to reducepower consumption by a UE is to operate using a discontinuous mode,e.g., discontinuous reception (DRX) and/or discontinuous transmission(DTX). In a DTX mode, the UE can turn off its transmitter and minimizefunctions of the receiver when there is a period of voice inactivity. ADTX mechanism uses transmission of a SID frame in place of a continuoustransmission of packetized silent periods to optimize power savings atthe UE. A SID frame can be a SID_UPDATE frame or a SID_FIRST frame. ASID_FIRST frame can indicate the beginning of a DTX mode of operation orperiod. A SID_UPDATE frame can contain comfort noise (CN) parametersthat convey information on the acoustic background noise. As describedherein, the term “SID frame” generally refers to the functions of aSID_UPDATE frame.

A UE can include a speech codec, such as an adaptive multi-rate (AMR)codec or an Adaptive Multi-Rate Wideband (AMR-WB) to convert analogspeech signals into digital packets for transmission over a wirelessnetwork. A speech codec can have two states, SPEECH and SILENCE for usein a DTX mode. A state of SILENCE indicates voice inactivity, while astate of SPEECH indicates voice activity. A speech codec includes avoice activity detector (VAD) that can allow the speech codec to reducethe number of transmitted bits and packets during a silent period. Inadvance of a silent period of voice inactivity, the speech codeccomputes CN parameters that characterize a background noise level andsubsequently transmits the CN parameters to a receiver of an endpointdevice to which the UE is connected. Sending the CN parameters atregular intervals during silent periods can be includes as part of theDTX mode of operation. In response to detecting a state of voiceinactivity, while operating in the DTX mode, the UE transmits SID framesto inform the receiver of the endpoint device of the voice inactivityand to provide instructions to terminate most receiver functions duringthe silent period. The endpoint device can generate CN during the silentperiod based on the received CN parameters. Subsequently, after sendingthe SID frames, the UE suspends operation of its transmitter to reducepower consumption until sending a following SID frame. Thus, both thetransmitting UE and the receiving endpoint device can conserve power byusing the DTX mode with voice activity/inactivity detection. The use ofspeech inactivity detection with SID frame communication to reduceaverage transmission rates in a DTX mode of operation is also referredto as a Source Controlled Rate (SCR) operation.

While in a SILENCE state, the UE transmits SID_UPDATE frames, containingCN parameters that convey information on the acoustic background noise.A SID_UPDATE frame can be sent periodically, e.g., every eight frames(160 ms), to control the operation and power consumption of the UE. TheCN parameters can be based on measurements of immittance spectralfrequency (ISF) or line spectral frequency (LSF) determined by thetransmitting UE. When a receiver of the endpoint device receives aSID_UPDATE frame with CN parameters, the endpoint device can generate asimilar background noise, which can be referred to as “comfort noise”,to provide to the listener during the silent period.

Embodiments described herein further minimize power consumption by atransmitting UE during a SILENCE state while maintaining an acceptablequality of service. A representative method utilizes the CN parametersin order to control transmission of the SID frames. By utilizing the CNparameters, a decision is made whether to send a SID_UPDATE frame, whento send a SID_UPDATE frame, how often to send SID_UPDATE frames, tocontrol transmission of the SID_UPDATE frames, while balancing qualityrequirements. A comparison of current (e.g., most recently determined)weighted averages of CN parameters to one or more previous (e.g.,determined earlier) weighted averages of CN parameters can be used bythe transmitting UE to determine when to transmit any SID_UPDATE frames.Specifically, a difference is determined between 1) a weighted averageof one or more CN parameters for a most recent sequence of encodedspeech frames and 2) a weighted average of one or more CN parameters fora previous sequence of encoded speech frames. When the differencebetween the weighted averages is greater than a difference threshold, aSID_UPDATE frame can be transmitted by the UE to the receiving endpointdevice. The current weighted average of one or more CN parameters isdetermined by averaging over a most recent sequence of encoded speechframes. The most recent sequence of encoded speech frames (or moregenerally, a first sequence of encoded speech frames) and a previoussequence of encoded speech frames (or more generally, a second sequenceof encoded speech frames) each can span an identical number ofconsecutive speech frames. The sequences of encoded speech frames canalso overlap by at least one speech frame and be offset from each otherby at least one speech frame. A speech frame can be a digitized andencoded data representation of audio speech, e.g., an output of a speechencoder.

Increasing an averaging time period over which weighted averages of CNparameters are calculated and increasing time between successiveSID_UPDATE frame transmissions, e.g., from a time period of eight speechframes, as defined in one or more 3rd Generation Partnership Project(3GPP) specifications and/or customarily used, to an extended timeperiod of N*8 speech frames, where N>1, can also reduce powerconsumption. SID_UPDATE frames can then be transmitted every N*8 speechframes rather than every eight speech frames. Furthermore, there can beadditional benefits when the aforementioned methods are combined, e.g.,a method can both increase an averaging time period to a sequence of N*8encoded speech frames, where N>1, and can also apply a differencethreshold for determining whether to transmit a SID_UPDATE frame. Theaveraging period can be increased, as well as a difference threshold canbe used to limit SID_UPDATE frame transmissions to circumstances inwhich a “sufficient” difference in the weighted average of the CNparameters occurs. This combined approach can further reduce powerconsumption at the UE.

This Summary is provided merely for purposes of summarizing some exampleembodiments so as to provide a basic understanding of some aspects ofthe subject matter described herein. Accordingly, it will be appreciatedthat the above-described features are merely examples and should not beconstrued to narrow the scope or spirit of the subject matter describedherein in any way. Other features, aspects, and advantages of thesubject matter described herein will become apparent from the followingDetailed Description, Figures, and Claims.

Other aspects and advantages of the embodiments described herein willbecome apparent from the following detailed description taken inconjunction with the accompanying drawings which illustrate, by way ofexample, the principles of the described embodiments.

BRIEF DESCRIPTION OF THE DRAWINGS

The described embodiments and the advantages thereof may best beunderstood with reference to the following description taken inconjunction with the accompanying drawings. These drawings are notnecessarily drawn to scale, and they are in no way intended to limit orexclude foreseeable modifications thereto in form and detail that may bemade by one having ordinary skill in the art at the time of thisdisclosure.

FIG. 1 illustrates a Long Term Evolution (LTE) wireless communicationsystem, in accordance with some embodiments.

FIG. 2A illustrates audio processing functions and an AMR or an AMR-WBcodec as utilized in UMTS and LTE wireless communication systems, inaccordance with some embodiments.

FIG. 2B illustrates Table 1 listing a set of TX_TYPE identifiers, inaccordance with some embodiments.

FIG. 2C illustrates Table 2 listing a set of RX_TYPE identifiers, inaccordance with some embodiments.

FIG. 3 illustrates timing of a silence indicator (SID) averagingprocedure for a DTX mode of operation.

FIGS. 4A and 4B illustrate timing of sequences of frames received at aUE, in accordance with some embodiments.

FIGS. 5A, 5B, and 5C illustrate flowcharts for determining SID_UPDATEframes in a DTX mode of operation, in accordance with some embodiments.

FIGS. 6A, 6B, 6C, and 6D illustrate additional flowcharts fordetermining SID_UPDATE frames in a DTX mode of operation, in accordancewith some embodiments.

FIG. 7 illustrates a block diagram of a wireless communication device,in accordance with some embodiments.

DETAILED DESCRIPTION

Reference will now be made in detail to representative embodimentsillustrated in the accompanying drawings. Although the embodiments ofthis disclosure are described in sufficient detail to enable one havingordinary skill in the art to practice the described implementations, itshould be understood that these examples are not to be construed asbeing overly-limiting or all-inclusive. It should be understood that thefollowing descriptions are not intended to limit the embodiments to onepreferred embodiment. To the contrary, it is intended to coveralternatives, modifications, and equivalents as can be included withinthe spirit and scope of the described embodiments as defined by theappended claims.

Representative examples of methods to save power in UEs, especially inthe discontinuous transmission mode are provided herein. These examplesare provided to add context to, and to aid in the understanding of, thesubject matter of this disclosure. It should be apparent that thepresent disclosure may be practiced with or without some of the specificdetails described herein. Further, various modifications and/oralterations can be made to the subject matter described herein, andillustrated in the corresponding figures, to achieve similar advantagesand results, without departing from the spirit and scope of thedisclosure.

In accordance with various embodiments described herein, the terms“wireless communication device,” “wireless device,” “mobile device,”“mobile station,” and “user equipment” (UE) may be used interchangeablyherein to describe one, or any number of, common consumer electronicdevice(s) that may be capable of performing procedures associatedvarious embodiments the disclosure. In accordance with variousimplementations, any one of these consumer electronic devices may relateto: a cellular phone or a smart phone, a tablet computer, a laptopcomputer or a netbook computer, a media player device, an electronicbook device, a MiFi® device, as well as any other type of electroniccomputing device having fourth generation (4G) LTE and LTE Advanced(LTE-A) communication capabilities. In various embodiments, thesecapabilities may allow a respective UE to communicate within various 4Gnetwork cells that can employ any type of LTE-based radio accesstechnology (RAT). A UE can communicate with network equipment such as abase transceiver station (BTS).

A Long Term Evolution (LTE) wireless communication system is an advancedgeneration wireless communication system and is sometimes referred to asa fourth generation (4G) wireless communication system. Specificationsfor LTE are provided by the 3rd Generation Partnership Project (3GPP),which unites six telecommunications standard development organizations(ARIB, ATIS, CCSA, ETSI, TTA, TTC), known as “Organizational Partners”and provides their members with a stable environment to produce Reportsand Specifications that define 3GPP technologies.

New generation mobile communication systems based on LTE technologiesaim to provide to customers a new mobile experience by providing higherdata rates and lower latencies to support new services and applications.However, the energy requirements for these new services and applicationscan be very demanding of limited battery power sources in mobilewireless devices, such as UEs. The development of new architectures andprocedures to build power-efficient and power-aware systems is a highpriority in the design of new generation wireless networks and wirelessdevices.

Voice over IP (VoIP) is an important service in 4G wirelesscommunication networks. One VoIP method is known as Voice over LTE(VoLTE). This VoIP method is based on the IP Multimedia Subsystem (IMS)network, with specific profiles for control and media planes of voiceservice on LTE. This VoIP method results in a voice service (control andmedia planes) being delivered as data flows within an LTE data bearer.Thus, there is no dependency on (or a requirement for) a legacyCircuit-Switched voice network to be maintained.

The following disclosure relates to methods and apparatus for poweroptimization for VoLTE service utilizing discontinuous transmission(DTX). Power consumption is a challenge for wireless devices, e.g., UEs,when providing a VoLTE service. One method to reduce power consumptionby a UE is to operate using a DRX mode and/or a DTX mode. In the DTXmode, the UE can turn off its transmitter and minimize functions of thereceiver when there is a period of voice inactivity. A DTX mechanismuses transmission of a silence descriptor (SID) frame to optimize thepower savings. A SID frame can be a SID_UPDATE frame or a SID_FIRSTframe. A SID_FIRST frame can indicate the beginning of a DTX mode ofoperation or period. A SID-UPDATE frame can contain comfort noise (CN)parameters that convey information on the acoustic background noise. Asdescribed herein, the term “SID frame” generally refers to the functionsof a SID_UPDATE frame.

A UE includes a speech codec, such as an AMR or an AMR-WB codec toconvert analog speech signals into digital packets for transmission overa wireless network. A speech codec can have two states, SPEECH andSILENCE for use in a DTX mode. A state of SILENCE indicates voiceinactivity, while a state of SPEECH indicates voice activity. A speechcodec includes a voice activity detector (VAD) that can allow the speechcodec to reduce the number of transmitted bits and packets during asilent period. In advance of a silent period of voice inactivity, thespeech codec computes CN parameters that are subsequently transmitted toa receiver of an endpoint device to which the UE is connected. Theoperation to send CN parameters at regular intervals during silentperiods is part of the DTX operation. By determining a state of voiceinactivity while operating in the DTX mode, the UE transmits a SID frameto inform the receiver of the endpoint device of the voice inactivityand provides instructions to terminate most receiver functions and togenerate CN in the endpoint device during the period of silence.Subsequently, the UE suspends operation of the transmitter. Thus, boththe transmitting UE and the receiving endpoint device can conserve powerby using the DTX mode with voice activity/inactivity detection. The useof speech inactivity detection with SID frame communication to reduceaverage transmission rates in a DTX mode of operation is also referredto as an SCR operation.

While in a SILENCE state, the UE transmits SID_UPDATE frames, containingCN parameters that convey information on the acoustic background noise.A SID_UPDATE frame can be sent every eight frames (160 ms) to controlthe operation and power consumption of the UE. The CN parameters can bebased on measurements of ISF parameters or LSF parameters. When areceiver of the endpoint device receives a SID_UPDATE frame with CNparameters, the endpoint device can generate CN, to provide to thelistener during the period of silence.

Embodiments disclosed herein further minimize power consumption by a UEoperating in a DTX mode in a SILENCE state. A representative methodutilizes the CN parameters in order to control how often to transmitSID_UPDATE frames. By utilizing the CN parameters, a decision is madewhether and/or when to send a SID_UPDATE frame, while balancing anyquality requirements. A comparison of the current and previous weightedaverages of the CN parameters can be used by the UE to determine when totransmit SID_UPDATE frames. Specifically, a difference is determinedbetween 1) a weighted average of one or more comfort parameters for amost recent sequence of speech frames and 2) a weighted average of oneor more comfort parameters for a previous sequence of speech frames.When the difference between the weighted averages is greater than adifference threshold, a SID_UPDATE frame can be transmitted by the UE.The current weighted average of one or more CN parameters is determinedby averaging over the most recent sequence of speech frames. The mostrecent sequence of speech frames (or more generally, a first sequence ofspeech frames) and a previous sequence of speech frames (or moregenerally, a second sequence of speech frames) can each span anidentical number of consecutive speech frames. The first and secondsequences of speech frames can overlap by at least one speech frame andcan be offset from each other by at least one speech frame. In someembodiments, the first and second sequences of speech frames can benon-overlapping (e.g., two consecutive sequences of speech frames.) Theweighted average of the CN parameters for the first sequence of speechframes can be determined by averaging over the CN parameters of theconsecutive speech frames in the first sequence. The weighted average ofthe CN parameters for the second sequence of speech frames can bedetermined by averaging over the CN parameters of the consecutive speechframes in the second sequence. A speech frame can be a digitized andencoded data representation of the audio speech, e.g., an output of aspeech encoder.

Increasing a time period over which averaging occurs, e.g., from eightspeech frames, as defined in one or more 3GPP specifications and/orcustomarily used, to N*8 speech frames (or more generally to a timeperiod longer than used for a “default” configuration or mode ofoperation) can further reduce power consumption at the UE. SID_UPDATEframes can be transmitted every N*8 speech frames rather than everyeight frames. Furthermore, additional benefits can be realized bycombining the aforementioned methods, i.e., increase the averagingperiod to N*8 speech frames and apply a difference threshold todetermine whether to transmit a SID_UPDATE frame. This combined approachcan further reduce power consumption at the UE. The method to increasethe averaging period to N*8 speech frames can include communicatingpackets between wireless devices via a wireless network while operatingin a proprietary communication mode, e.g., in a mode in which eachwireless device recognizes that the other wireless device can support anextended mode in which SID_UPDATE frames are spaced further apart than a“default” setting. The wireless device determines when the secondwireless device is capable of transmitting a SID_UPDATE frame using anextended time period between SID_UPDATE frames. The extended time periodcan be greater than eight speech frames, in some embodiments. Theproprietary communication mode can be implemented as a communicationmode between wireless devices that exchange directly or indirectlyinformation about their settings and/or capabilities. In someembodiments, the extended mode can be used between two wireless devicesthat each include an iOS operating system. In some embodiments, theextended mode can be used between an iOS device and another iOS device.In some embodiments, the extended mode can be used between an iOS deviceand a device using a different operating system, e.g., an Android™device. In some embodiments, the extended mode can be used between twodevices that use the same operating system, e.g., both Android™ devices.

At a receiving endpoint device, spectral information (e.g., ISF or LSFparameters) and energy information that is received in SID_UPDATE framescan be interpolated between successive SID_UPDATE frames to determine CNparameters for CN generation. In some embodiments, an interpolationfactor can be adjusted based on a length of time between successiveSID_UPDATE frames, as the time between SID_UPDATE frames may not beconstant. In some embodiments, when a SID_UPDATE frame is not received,a previous SID_UPDATE frame, e.g., the last received SID_UPDATE frame,can be reused for CN generation at the receiving endpoint device.

In an embodiment, a method for SID communication between two“compatible” devices that share a common capability (such as usingversions of the same operating system) can be provided. In someembodiments, two iOS devices can use a particular method for SID framegeneration and transmission at a transmitting device and for SID framereception and CN generation at the receiving endpoint device. The methodcan be used to address compatibility issues with non-iOS devices,specifically concerning their expectation of the reception and frequencyof occurrence of SID_UPDATE frames. Adaptation of an algorithm for iOSonly applications can use the fact that for many iOS services, such asiMessage®, FaceTime®, etc., a device identification (ID) is stored in acentral server. Prior to altering SID generation and SID_UPDATEs, anoriginating device can check whether a receiving endpoint device is aniOS device. The originating device can check for properties of thereceiving endpoint device because, the originating device can obtain oneor more IDs for the receiving endpoint device, such as MSISDN, SIP, URI,etc. When it is confirmed that both devices are iOS devices, a frequencyof SID_UPDATE frame transmission can be further reduced. A compatibleiOS device receiver can reuse previous SID_UPDATE frames or useextrapolation of previous SID_UPDATE frames to generate CN in theendpoint device.

DTX operational modes can allow the radio transmitter of a UE to beswitched off most of the time during speech pauses to save power in theUE. A secondary benefit using DTX modes can be a reduction in theoverall interference level over the radio frequency “air” interface. AnDTX mechanism can include the following functions:

-   -   a voice activity detector (VAD) on the transmit (TX) side;    -   evaluation of the background acoustic noise on the transmit (TX)        side, in order to transmit characteristic parameters to the        receive (RX) side; and    -   generation on the receive (RX) side of a similar noise, referred        to as CN, during time periods when voice packet radio        transmission from the TX side is switched off.

During a normal voice conversation, participants can alternatively speaksuch that on average each direction of transmission can be occupiedabout 50% of the time. As previously noted, the DTX operational modewith voice activity detection and SID frame transmission can result in alower bit-rate than normally used for encoding speech. A wirelessnetwork can adapt its transmission scheme to take advantage of theresulting variable bit-rate, e.g., to share radio frequency resources inthe access network more efficiently among multiple UEs.

CN is a synthetic background noise used in wireless communications tofill the artificial silence in a transmission resulting from voiceactivity detection. Some wireless systems use voice activity detectionin which low speech volume levels can be ignored by a transmittingwireless device. For wireless systems, this can save bandwidth and powerconsumption by transmitting nothing when the source volume falls below acertain threshold, leaving only louder sounds (such as the speaker'svoice) to be sent.

AMR Codecs can support a DTX operational mode that includes voiceactivity detection, silence description (e.g., using SID frames), and CNgeneration to fill speech pauses. When the speech encoder at thetransmitting UE detects voice inactivity, speech frames are nottransmitted in order to reduce power consumption of the UE, reduceinterference on the radio interface, and reduce loading. A receivingspeech decoder in a receiving endpoint device can fill speech pauseswith simulated background noise, referred to as “comfort noise” (CN), tominimize the contrast between pauses and active speech. SID_UPDATEframes are regularly sent from the transmitting UE to the receivingendpoint device during voice inactivity to match the generated CN tobackground noise at the transmitting UE. This process can be especiallyimportant at the onset of a subsequent talk spurt, and thereforeSID_UPDATE frames used for CN generation should not be too “old”, whenspeech resumes, as the simulated background noise level provided to theuser at the receiving endpoint device should be comparable to the actualbackground noise level that will be transmitted in the ensuing speechframes. Per one or more 3GPP specifications, a radio subsystem of the UEcan use a fixed timing for the transmission of SID_UPDATE frames. Inparticular, one or more 3GPP specifications require that SID_UPDATEframes can be transmitted during speech pauses during regular intervals,e.g., every eight frames or 160 ms.

The embodiments disclosed herein characterize the voice inactivityperiods and provide for transmitting SID_UPDATE frames using in timeintervals spaced further apart than every eight frames, whilemaintaining an acceptable quality of service. A longer time interval forSID_UPDATE frame transmission can reduce power consumption inasmuch asthe transmitter of the UE can be inactive while the receiver at thereceiving endpoint device (e.g., another UE) can remain in a monitoringmode for longer periods of time. Methods and apparatus for embodiment ofthe present invention are discussed below with reference to the Figures.However, those skilled in the art will readily appreciate that thedetailed description given herein with respect to these Figures is forexplanatory purposes only and should not be construed as limiting.

FIG. 1 illustrates a representative Long Term Evolution (LTE) wirelessnetwork 100, e.g., as specified by 3GPP, that can include user equipment(UE) 102 connected by one or more radio links 126 to one or more radiosectors 104 provided by an evolved radio access network 122. Each radiosector 104 can represent a geographic area of radio coverage emanatingfrom an associated evolved Node B (eNodeB) 110 using a radio frequencychannel operating at a selected frequency. In some embodiments, radiosectors 104 can also be referred to as cells. Each eNodeB 110 cangenerate one or more radio sectors 104 to which the UE 102 can connectby one or more radio links 126. In some embodiments of an LTE wirelessnetwork 100, the UE 102 can be connected to more than one radio sector104 simultaneously. The multiple radio sectors 104, to which the UE 102can be connected, can emanate from a single eNodeB 110 or from separateeNodeB's 110. A group of eNodeB's 110 can be referred to as an evolvedUniversal Mobile Telecommunications System (UMTS) radio access network(eUTRAN) 106. Typically, each eNodeB 110 in an eUTRAN 106 can include aset of radio frequency transmitting and receiving equipment mounted onan antenna tower and a radio controller for controlling and processingtransmitted and received radio frequency signals. The eNodeB 110 of theeUTRAN 106 can manage the establishment, maintenance and release of theradio links 126 that connect the UE 102 to an evolved radio accessnetwork 122. In some embodiments, the eNodeB 110 can provide access to awireless network based on an LTE technology, such as an LTE wirelessnetwork and/or LTE-Advanced (LTE-A) wireless network. It will beappreciated, however, that various example embodiments are not limitedto application in LTE wireless network systems.

Radio resources that form the radio links 126 in the radio sectors 104can be shared among multiple UEs 102 using a number of differentmultiplexing techniques, including time division, frequency division,code division, space division and combinations thereof. A radio resourcecontrol (RRC) signaling connection can be used to communicate betweenthe UE 102 and the eNodeB 110 in the eUTRAN 106 of the evolved radioaccess network 122 including requests for and dynamic allocations ofradio resources to multiple UEs 102. The UE 102 can be connected to theevolved radio access network 122 through one or more radio sectors 104simultaneously.

The evolved radio access network 122, which provides radio frequency airlink connections to the UE 102, connects also to an evolved packet corenetwork 120. The LTE wireless network 100 can be designed to operate asa packet switched network exclusively. The evolved packet core network120 can include serving gateways 112 that interconnect the evolved radioaccess network 122 to public data network (PDN) gateways 116 thatconnect to external internet protocol (IP) networks 118. The eNodeB's110 can also be connected to a mobility management entity (MME) 114 thatcan provide control over connections for the user equipment 102. TheeNodeB 110 can control allocation of radio resources for the radio links126 to the user equipment 102. The eNodeB 110 can communicate pagingmessages to the user equipment 102, including paging messages toestablish an RRC connection with the UE 102 and to transition the UE 102from an RRC idle state to an RRC connected state. The eNodeB 110 canschedule radio resources for the UE 102 and provide indications of radioresource allocations using signaling messages communicated in a physicaldownlink control channel (PDCCH). The UE 102 can monitor the PDCCH todetermine when radio resources are assigned to the particular UE 102 fordownlink transmission from the eNodeB 110 or for uplink transmission tothe eNodeB 110. The eNodeB 110 can also broadcast System InformationBlock (SIB) messages periodically to inform the UE 102 about propertiesof the radio sectors 104 and/or for services provided by the eNodeB 110.The Mobility Management Entity (MME) 114 in the Evolved Packet CoreNetwork 120 can be a key control node for the LTE access network and canbe responsible for tracking and paging UE's 102 when in an idle mode.

LTE wireless network 100 can support VoLTE service using a VoIP specificprotocol stack with signaling radio bearers and speech radio bearers. AVoLTE service requires capabilities at both the end-user device (e.g.,UE 102) and the LTE wireless network 100. To provide VoIP service, theUE 102 and includes a speech codec that can periodically generate blocksof data. There is a wide range of speech codecs available, but it may beassumed that the UE 102 and the LTE network 100 can support an AMRspeech codec that provides a full set of modes, e.g., eight differentbit rates. The UE 102, in some embodiments, can include support for anAMR wideband codec (WB-AMR) that provides additional modes. The AMRspeech coder can operate as a narrowband or a wideband speech codec.Both AMR and WB-AMR codecs use a 20 msec. frame structure. The AMRspeech codec includes a multi-rate speech coder, a source controlledrate (SCR) operation using including a voice activity detector and a CNgeneration system, and an error concealment mechanism to combat theeffects of transmission errors and lost packets.

The following terms and definitions are used in this specification:

-   -   AMR: Adaptive Multi-Rate.    -   AMR-WB: Adaptive Multi-Rate Wideband.    -   Accepted SID frame: traffic frame which is flagged with SID=“1”        or SID=“2”.    -   Bad traffic frame: traffic frame flagged BFI flag=“1” (Bad Frame        Indication).    -   CN: comfort noise. Frame: time interval of 20 msec.        corresponding to a time segmentation of the AMR speech encoder;        also used as a short term for a traffic frame.    -   Frame: time interval of 20 msec. corresponding to the time        segmentation of the full rate speech encoder, also used as a        short term for a traffic frame.    -   Good speech frame: good traffic frame which is not an accepted        SID frame.    -   Good traffic frame: traffic frame flagged BFI flag=“0”.    -   IFS: Immittance Spectral Frequency.    -   Invalid SID frame: accepted SID frame which was not classified        as valid SID frame. This frame is not valid for updating CN        parameters, but the frame conveys information that CN        generations should be started or continued.    -   LSF: Line Spectral Frequency    -   LSP: Line Spectral Pair.    -   LPC—linear predictive coding; interpolation of the CN parameters        values received in previous (e.g., the last two) valid SID        frames.    -   Lost SID frame: unusable frame received when the RX DTX handler        is generating CN and a SID frame is expected (Time Alignment        Flag, TAF=“1”).    -   Lost speech frame: unusable frame received when the RX DTX        handler is passing on traffic frames directly to a speech        decoder.    -   N_(elapsed): Number of elapsed frames since the last updated SID        frame.    -   R0: Frame energy value/interpolation of the CN parameters values        received in the last two valid SID frames.    -   RSS: Radio Subsystem    -   RX_TYPE: Classification of the received traffic frame.    -   SCR: Source Controlled Rate operation    -   SID (silence descriptor) frame: CN frames. It can convey        information on the acoustic background noise and/or inform the        decoder that it should start generating background noise. SID        frame is characterized by a SID code word.    -   SID_FIRST: AMR or AMR-WB frame used to indicate the beginning of        a DTX period (SP=0).    -   SID_UPDATE: AMR or AMR-WB frame used to convey comfort noise        characteristics during a DTX period (SP=0).    -   SID code word: fixed bit pattern for labelling a traffic frame        as a SID frame.    -   SID field: bit positions of the SID code word within a SID        frame.    -   SP flag: Boolean flag, generated by the TX DTX handler,        indicating the presence of a speech frame (“1”) or the presence        of a SID frame (“0”).    -   Speech frame: traffic frame that cannot be classified as a SID        frame.    -   TAF flag: Time Alignment Flag. Boolean flag that marks with        TAF=1 traffic frames that are aligned with the Slow Associated        Control Channel (SACCH) multi-frame structure. The next SID        frame is expected at the decoder when TAF=1.    -   Traffic frame: block of 244 information bits transmitted on the        Enhanced Full Rate speech traffic channel. A traffic frame can        be a speech frame or a SID frame.    -   TX_TYPE: Classification of the transmitted traffic frame.    -   Unusable frame: bad traffic frame that is not an accepted SID        frame.    -   VAD: voice activity detector.    -   VAD flag: Voice Activity Detection flag. Boolean flag generated        by a VAD algorithm indicating the presence (“1”) or the absence        (“0”) of a speech frame.    -   Valid SID frame: good traffic frame flagged with SID=“2”. This        frame is valid for updating CN parameters at any time.

FIG. 2A illustrates an encoder/decoder (codec) 200 including audioprocessing functions and AMR or AMR-WB speech encoding and decodingfunctions that can be utilized in LTE wireless communication systems.Codec 200 includes processing elements to perform functions of amulti-rate speech encoder and decoder, a DTX mechanism to detect voiceactivity and generate CN, and an error concealment mechanism to combatthe effects of transmission errors and lost packets. As shown on FIG.2A, codec 200 includes voice activity detector 202 (VAD 202), speechencoder 203, comfort noise parameter computation TX 204, and DX controland operation TX 201 in a transmitter 218. Codec 200 also includesspeech frame substitution 205, speech decoder 206, comfort noisegeneration RX 207, and DX control and operation RX 211 in a receiver220. Comfort noise parameter computation TX 204 computes CN parametersin the transmitter 218, while comfort noise generation RX 207 generatesCN based on received CN parameters in the receiver 220. The combinationof the VAD 202, speech encoder 203, and comfort noise parametercomputation TX 204 is referred to as the TX DTX handler 208. Thecombination of the speech frame substitution 205, speech decoder 206,and comfort noise generation RX 207 is referred to as the RX DTX handler210. DX control and operation TX 201 and DX control and operation RX 211provide functionality to support the DTX mechanism at the transmitter218 and the receiver 220 respectively. The Transmitter 218 includes DXcontrol and operation TX 201, TX DTX handler 208, and analog-to-digital(A/D) converter 213. The Receiver 220 includes DX control and operationRX 211, RX DTX handler 210, and digital-to-analog (D/A) converter 215.In FIG. 2A, audio processing elements such as the A/D converter 213 andthe D/A converter 215 are included to show a complete speech pathbetween an audio input and an audio output of the UE 102.

As previously described herein, codec 200 can be an AMR codec or anAMR-WB codec. The AMR codec is a single integrated speech codec witheight source rates from 4.75 kbit/s to 12.2 kbit/s, and a low ratebackground noise encoding mode. The AMR-WB codec is a single integratedspeech codec with nine source rates from 6.60 kbit/s to 23.85 kbit/s,and a low rate background noise encoding mode. The AMR and AMR-WB codecscan be capable of switching their bit rates every 20 ms speech frame.

The signals shown in FIG. 2A include the following:

-   -   1) Speech 214—input to transmitter 218.    -   2) Audio Output 216—output from receiver 220.    -   3) Voice Activity Detector (VAD) flag 222.    -   4) Encoded speech frame 226.    -   5) Silence Descriptor (SID) frame 228.    -   6) SP Flag 224, TX_TYPE, 3 bits, indicates whether information        bits are available and if they are speech or SID information.    -   7) Information bits (Info Bits) 236 delivered to the wireless        network.    -   8) Information bits (Info Bits) 238 received from the wireless        network.    -   9) Bad Frame Indicator (BFI) 240, RX_TYPE, the type of frame        received quantized into three bits.    -   10) Silence Descriptor (SID) flag 242.    -   11) Time Alignment Flag (TAF) 244 marks the position of the SID        frame within the SACCH (Slow Associated Dedicated Control        Channel) multi-frame.

FIG. 2B illustrates Table 1 listing a set of TX_TYPE identifiers. FIG.2C illustrates Table 2 listing a set of RX_TYPE identifiers. The TX_TYPEidentifiers and RX_TYPE identifiers can apply to a DTX mode ofoperation. FIG. 3 illustrates timing of a silence indicator (SID)averaging procedure for a DTX mode of operation. FIGS. 2B, 2C and 3 arerepresentative of SID averaging as defined in one or more 3GPPspecifications.

In reference to FIG. 2A and FIG. 3 the following functions can be usedas part of a DTX mode of operation: (1) the voice activity detector (VAD202) on the TX side; (2) evaluation of the background acoustic noise onthe TX side (comfort noise parameter computation TX 204), in order totransmit characteristic parameters to the RX side; (3) generation of CNon the RX side during periods when no normal speech frames are received(comfort noise generation RX 207). A silence descriptor (SID) frame canbe sent at regular intervals and can provide CN parameter information tothe RX side. The SID frame 228 is indicated in FIG. 2A.

The VAD 202 determines voice activity (and voice inactivity). The inputto the VAD 202 can be a digitized and encoded version of Speech 214together with a set of parameters computed by the speech encoder 203.The VAD 202 can use this information to decide whether each 20 ms speechcoder frame contains a signal that should be transmitted. The output ofthe VAD 202 is a Boolean flag, namely VAD Flag 222 indicating thepresence of such signals. The VAD 202 can use parameters of the speechencoder 203 to compute the VAD Flag. A background noise level can beestimated in one or more frequency bands. An intermediate VAD decisioncan be calculated by comparing an input signal-to-noise ratio (SNR) toan adaptive SNR threshold. The SNR threshold is adapted based onmeasured noise levels and on long-term speech estimates.

TX side Functions: In TX DTX handler 208, the comfort noise parametercomputation TX 204 includes an evaluation algorithm for an AMR or anAMR-WB speech codec:

-   -   For an AMR codec, the CN evaluation algorithm can use        unquantized Linear Prediction (LP) parameters, using a Line        Spectral Pair (LSP) representation. The CN evaluation algorithm        can compute the following CN parameters to assist in CN        generation:        -   1. Weighted average LSF parameter vector (e.g., a weighted            average of LSF parameters of the eight most recent frames);        -   2. Weighted average logarithmic frame energy parameters            (e.g., a weighted average of logarithmic frame energy            parameters of the eight most recent frames).    -   For an AMR-WB codec, the CN evaluation algorithm can use        unquantized LP parameters, using an ISF representation. The CN        evaluation algorithm can compute the following CN parameters to        assist in CN generation:        -   1. Weighted average ISF parameter vector (e.g., a weighted            average of ISF parameters of the eight most recent frames);        -   2. Weighted average logarithmic frame energy parameters            (e.g., a weighted average of logarithmic frame energy            parameters of the eight most recent frames).            These CN parameters can provide information about an energy            level (averaged logarithmic frame energy) and a spectrum            (ISF or LSF parameter vector) representation of the            background noise. As previously described herein, the CN            parameters can be encoded into a SID frame for transmission            to the RX side. In some embodiments described herein, the            averaging period can be based on more than eight speech            frames.

FIG. 3 illustrates timing for a SID frame averaging procedure for a DTXmode of operation. The VAD flag is a Boolean flag, generated by a VADalgorithm, which indicates the presence (“1”) or the absence (“0”) of aspeech frame. The SP flag is a Boolean flag, generated by the TX DTXhandler, which indicates the presence of a speech frame (“1”) or thepresence of a SID frame (“0”). The first SID frame after a period ofactive speech can also serve to initiate CN generation on the receiveside, as the first SID frame is always sent at the end of a speechburst, i.e., before transmission terminates. Also, the CN parameters tobe encoded into a SID frame can be calculated over eight consecutiveframes marked with VAD=0. Prior to averaging the ISF (or LSF) parametersover the CN averaging period, a median replacement can be performed onthe set of ISF (or LSF) parameters to be averaged to remove parametersthat are not characteristic of the background noise on the transmitside.

RX side Functions: RX DTX handler 210 can perform speech decoding, CNcomputation, and SID frame detection. Whenever a good speech frame isdetected by the RX DTX handler 210, the good speech frame can passdirectly to speech decoder 206. Whenever a lost speech frame or lost SIDframes are detected, a substitution or mutation can be applied. A validSID frame can result in CN generation.

In general, the CN generation can be started or updated whenever a validSID frame is received. When speech frames are received by the decoder,the LP parameters and the energy parameters of the last seven speechframes can be kept in memory. The decoder can count the number of framesthat elapse after the last SID frame is updated.

As soon as a SID frame is received, CN can be generated at the decoder.Initial SID frame parameters for a “silent” period are computed from CNparameters stored during frames 39-45, as illustrated in FIG. 3. Theaveraging procedure for obtaining the CN parameters for the first SIDframe can be as follows: (1) when a speech frame is received, the ISF orLSF parameter vectors can be decoded and stored in memory; moreover, thelogarithmic frame energy of the decoded signal can also be stored inmemory; (2) averaged values of the quantized ISF (or LSF) parametervectors and the averaged logarithmic frame energy of the decoded framescan be computed and used for CN generation. In some embodiments, CNparameters from a previous SID_UPDATE frame can be used.

FIG. 3 also illustrates timing of a SID frame as part of a DTX mode ofoperation. As shown in FIG. 2A, the transmit TX DTX handler 208 includesVAD 202, Speech encoder 203, and comfort noise parameter computation TX204. The TX DTX handler 208 continuously passes traffic frames,individually marked by an SP flag. This binary flag is redundant to theSID code word labelling. SP flag=“1” indicates a speech frame, and SPflag=“0” indicates a SID frame. The scheduling of the frames fortransmission on the radio frequency air interface of the UE 102 can bebased on values of the SP flag.

To allow verification of the TX DTX handler 208 functions, all framesbefore a reset of the system can be treated as if there were speechframes of an infinitely long time. Therefore, and in order to ensure thecorrect estimation of CN parameters at the receiver side, the firstseven frames after a reset, or after enabling the DTX mode of operation,can always be marked with SP flag=“1” (TX_TYPE=“SPEECH_GOOD”), even ifVAD flag=“0”.

VAD 202 operates continuously to assess whether the input signalcontains speech or not. The output of VAD 202 is a binary-valued VADflag (VAD flag=“1” or VAD flag=“0”, respectively) on a frame-by-framebasis. The VAD flag controls indirectly, via the TX DTX handler 208operations, the overall DTX mode of operation on the transmitter side.Whenever VAD flag=“1”, the speech frame output from the speech encoder203 along with mode information can be transmitted, marked with SPflag=“1” (TX_TYPE=“SPEECH_GOOD”).

At the end of a speech burst (e.g., during a transition from VADflag=“1” to VAD flag=“0”), it takes eight consecutive frames to make anew updated SID frame analysis available at the receiver side. Normally,the first seven speech frames output from the speech encoder 203 afterthe end of a speech burst can be transmitted, marked with SP flag=“1”(TX_TYPE=“SPEECH_GOOD”). The end of a speech burst is then indicated bypassing the eighth frame after the end of the speech burst marked withSP flag=“0”. FIG. 3 illustrates an eight-frame SID averaging period,over which the CN parameters are averaged, in particular the R0 (frameenergy value) and LPC coefficients are averaged during the eight-frameSID averaging period. Updating of the CN parameters, namely the frameenergy and LPC coefficients, can occur each time a valid SID frame isreceived at the receiver. As part of the updating the CN parameters canbe interpolated over a SID update period to obtain smooth transitionsbetween different time periods having different amounts of backgroundnoise (and/or between speech bursts and silent periods).

FIG. 4A illustrates a diagram 400 of timing for sequences of framesreceived at the UE 102, in accordance with some embodiments. Thesequences of frames shown include twelve successive frames. A “second”(or more generally a previous) frame is labeled as frame 11, and a“first” (or more generally a current) frame is labeled as frame 12.Frames 4 to 11 can be referred to as a “second” sequence of frames,while frames 5 to 12 can be referred to as a “first” sequence of frames.Hence, the first sequence of frames is a sequence of frames includingthe first frame as the most recent frame, while the second sequence offrames includes the second frame as its most recent frame. The first andsecond sequences of frames can overlap by at least one frame. In therepresentative sequences illustrated in FIG. 4A, the two sequences offrames overlap by seven frames. For the representative sequence offrames shown in FIG. 4A, the first sequence of frames and the secondsequence of frames each span a length of eight frames. Hence, N=1. Thefirst sequence of speech frames and the second sequence of speech framescan each span eight consecutive speech frames. A time interval betweensuccessively transmitted SID_UPDATE frames can equal or exceed a timespan of eight successive speech frames. The term “first sequence offrames” can also be referred to as the “first sequence”. The term“second sequence of frames” can also be referred to as the “secondsequence”. The terms “sequence of frames”, “sequence of speech frames”and “sequence of encoded speech frames” are equivalent terms. Thisnomenclature also applies to FIG. 3.

FIG. 4B illustrates a diagram 450 of timing for additional sequences offrames received at the UE 102, in accordance with some embodiments. Thesequences of frames shown in FIG. 4B span 28 frames. For therepresentative sequences illustrates in FIG. 4B, the “second” frame islabeled as frame 27, while the “first” frame is labeled as frame 28.Therefore, frames 4 to 27 can be referred to as the second sequence offrames, and frames 5 to 28 can be referred to as the first sequence offrames. The first and second sequences can each include an integermultiple of eight frames, e.g., N*8 speech frames, where N=3. (Moregenerally, each sequence can span an identical number of frames.) Thetime period separating successively transmitted SID_UPDATE frames canequal a time period of N*8 successive speech frames, where N is aninteger greater than one.

In some embodiments, the first sequence of speech frames includes thefirst speech frame as a most recent speech frame in the first sequenceof speech frames, and the second sequence of speech frames includes asecond speech frame as the most recent speech frame in the secondsequence of speech frames. The first sequence of speech frames and thesecond sequence of speech frames each (a) span an identical number ofconsecutive speech frames, (b) overlap by at least one speech frame and(c) are offset from each other by at least one speech frame. In FIG. 4A,the first and second sequences of speech frames each span eightconsecutive speech frames, overlap by one speech frame and are offsetfrom each other by one speech frame. For FIG. 4B, the first and secondsequences of speech frames each span 24 consecutive speech frames,overlap by one speech frame and are offset from each other by one speechframe. For the embodiments illustrated in FIG. 4A and FIG. 4B, the firstand second sequences of frames can also be referred to as an “n^(th)”and an “(n−1)^(th)” sequence of speech frames, respectively. And thefirst and second speech frames can be referred to as the n^(th) and the(n−1)^(th) speech frames respectively.

FIGS. 5A, 5B, and 5C illustrate a representative embodiment of a methodto determine the transmission of SID_UPDATE frames in a DTX mode ofoperation. FIGS. 5A, 5B, and 5C illustrate flowcharts 500, 550, and 570for adapting time intervals between SID_UPDATE frames at the UE 102, inaccordance with some embodiments. Flowcharts 500, 550, and 570 includesteps for methods in which the UE 102 determines whether a SID_UPDATEframe should be transmitted. The method includes one or more of thefollowing steps to determine whether a SID_UPDATE frame should betransmitted.

-   -   (a) Determining a difference between (i) a weighted average of        one or more CN parameters for a most recent sequence of frames        and (ii) a weighted average of one or more CN parameters for a        previous sequence of frames. When the difference between the        weighted averages of CN parameters exceeds a difference        threshold, the UE 102 transmits a SID_UPDATE frame.    -   (b) Determining whether the weighted average of the one or more        CN parameters for the most recent sequence of frames exceeds a        parameter threshold. If yes, the UE 102 transmits a SID_UPDATE        frame.    -   (c) Determining after entering the Silence state whether a time        elapsed until a first SID_UPDATE frame is transmitted or a time        between SID_UDATE frames exceeds a time threshold. (i) When a        first SID_UPDATE frame has not been transmitted, after entering        the Silence state, the method determines whether the time        elapsed since entering the Silence state exceeds a first time        threshold. When the time elapsed since entering the Silence        state exceeds the first time threshold, the UE 102 transmits a        SID_UPDATE frame. When the time elapsed since entering the        Silence state does not exceed a first time threshold, the UE 102        does not transmit a SID_UPDATE frame. (ii) When a first        SID_UPDATE frame has been transmitted, the method determines        whether the time elapsed since transmitting the most recent        SID_UPDATE frame, while in the Silence state, exceeds a second        time threshold. When the time elapsed since transmitting the        most recent SID_UPDATE frame, while in the Silence state,        exceeds a second time threshold, the UE 102 transmits a        SID_UPDATE frame. When the time elapsed since transmitting the        most recent SID_UPDATE frame, while in the Silence state, does        not exceed a second time threshold, the UE 102 does not transmit        a SID_UPDATE frame.        In some embodiments, the steps for item (b) or item (c) can be        optional. In some embodiments, one or more of the steps (a),        (b), and (c) can be used alone or in combination as a set of        conditional tests to determine whether to send a SID_UPDATE        frame while in the Silence state.

The following steps can be performed at the UE 102 in a representativemethod as illustrated in flowcharts 500, 550, and 570.

-   -   Step 501: Is a SILENCE state detected? If yes, proceed to step        502. If no, the method ends.    -   Step 502: Measure one or more characteristics of a first speech        frame received by the UE 102.    -   Step 503: Compute one or more CN parameters based on one or more        characteristics of the first speech frame. For an AMR codec, the        CN parameters can be based on a set of weighted, averaged LSF        parameter vectors and a set of averaged logarithmic frame energy        parameters. For an AMR-WB codec, the CN parameters can be based        on a set of weighted, averaged ISF parameter vectors and a set        of averaged logarithmic frame energy parameters.    -   Step 504: Determine a weighted average of CN parameters of the        first sequence of speech frames, where the first sequence of        speech frames is the most recent sequence of speech frames, and        the first speech frame is the most recent frame in the first        sequence of speech frames.    -   Step 505: Store the weighted average of CN parameters of the        first sequence of speech frames.    -   Step 506: Does the weighted average of the CN parameters of the        first sequence of speech frames exceed a parameter threshold? If        yes, proceed to step 513, if no, proceed to step 507.    -   Step 507: Retrieve from storage a weighted average of CN        parameters of a second sequence of speech frames, where the        second speech frame is the most recent frame in the second        sequence of speech frames.    -   Step 508: Determine a difference between the weighted average of        CN parameters of the first sequence of speech frames (most        recent sequences of frames) and the weighted average of the CN        parameters of the second sequence of speech frames (previous        sequence of frames).    -   Step 509: Does the difference between the CN weighted average of        the first sequence (most recent sequence of speech frames) and        the CN weighted average of the second sequence (previous        sequence of speech frames) exceed a difference threshold? If        yes, proceed to step 513, if no, proceed to step 510.    -   Step 510: Since entering the Silence state, has a SID_UPDATE        frame been transmitted? If yes, proceed to step 512. If no,        proceed to step 511.    -   Step 511: Does the time since entering the Silence state exceed        a first time threshold? If yes, proceed to step 513. If no,        proceed to step 514.    -   Step 512: Does the time elapsed since transmitting the most        recent SID_UPDATE frame exceed a second time threshold? If yes,        proceed to step 513. If no, proceed to step 514.    -   Step 513: Transmit a SID_UPDATE frame to a receiving endpoint        device.    -   Step 514: Do not transmit a SID_UPDATE frame to the receiving        endpoint device.        In some embodiments, steps 506 and 510-512 can be optional        steps. In some embodiments, one or more of the conditional tests        illustrated in steps 506, 509, and 510-512 can be used alone or        in combination to determine whether to send a SID_UPDATE frame.        Thus, the method illustrated can include one or more tests for a        parameter threshold, a difference threshold, and/or time        thresholds.

In some embodiments, step 509 is executed as follows: For an AMR codec,the SID_UPDATE frame is not transmitted to the receiving endpoint devicewhen a difference between the weighted average of the CN parameters,which include the LSF parameter vectors, for the first and secondsequences is less than an LSF threshold. Conversely, when the differencebetween the weighted average of the CN parameters, which include the LSFparameter vectors, for the first and second sequences equals or exceedsthe LSF threshold, the SID_UPDATE frame is transmitted. Similarly, foran AMR-WB codec, the SID_UPDATE frame is not transmitted to thereceiving endpoint device when a difference between the weighted averageof the CN parameters, which include the ISF parameter vectors, for thefirst and second sequences is less than an ISF threshold. Conversely,when the difference between the weighted average of the CN parameters,which include the ISF parameter vectors, for the first and secondsequences equals or exceeds the ISF threshold, the SID_UPDATE frame istransmitted. In some embodiments, a comparison of logarithmic frameenergy parameters can be used in place of or in addition to LSF/ISFparameter vectors to determine whether to send the SID_UPDATE frame tothe receiving endpoint device, e.g., by comparing logarithmic frameenergy parameter values (or averaged values) to an energy threshold.

The method illustrated in FIGS. 5A, 5B, and 5C can allow for SID framesto be transmitted spaced apart by different time intervals based on thecomparison of the weighted averages to a difference threshold, aparameter threshold, and/or time thresholds. One or more 3GPPspecifications presently require SID_UPDATE frames to be transmittedevery eight frames or equivalently every 160 msec (for 20 msec frames).With the method illustrated in FIGS. 5A, 5B, and 5C, the time intervalbetween SID_UPDATE frame transmissions can be equal to or greater thaneight frames. By transmitting SID_UPDATE frames less often, the UE'spower consumption can be reduced.

FIG. 6A illustrates a flowchart 600 for adjusting the time intervalbetween SID_UPDATE frames, in accordance with some embodiments.Flowchart 600 illustrates an averaging period of N*8 frames, where N isan integer greater than one. Per FIG. 6A, the method includes thefollowing steps performed at the UE 102:

-   -   Step 601: Communicate packets with a second wireless device via        a wireless network while operating in a proprietary        communication mode where the wireless device determines when the        second wireless device is capable of transmitting a SID frame        using an extended time period, e.g., a time period that exceeds        eight speech frames.    -   Step 602: Is a SILENCE state detected? If yes, proceed to step        503. If no, the method ends.    -   Step 603: Measure one or more characteristics of a first speech        frame received by the UE 102.    -   Step 604: Compute one or more CN parameters based on the        measured one or more characteristics of the first speech frame.        For an AMR codec, the CN parameters can be based on a set of        weighted average LSF parameter vectors and a set of weighted        average logarithmic frame energy parameters. For an AMR-WB        codec, the CN parameters can be based on a set of weighted        average ISF parameter vectors and a set of weighted average        logarithmic frame energy parameters.    -   Step 605: Determine a weighted average of CN parameters of the        most recent N*8 frames (first sequence), where the first frame        is the most recent frame in the first sequence.    -   Step 611: Transmit a SID_UPDATE frame to the second wireless        device every N*8 frames.

FIGS. 6B, 6C, and 6D illustrate additional flowcharts 650, 670, and 690for adjusting a time interval between SID_UPDATE frames. Flowcharts 650,670, and 690 combine elements of flowcharts 500, 550, 570, and 600, toincrease an averaging period to N*8 frames and to apply one or morethresholds to decide whether to transmit a SID frame. Per flowcharts650, 670, and 690, a representative method includes the following stepsperformed at the UE 102:

-   -   Step 651: Communicate packets with a second wireless device via        a wireless network while operating in a proprietary        communication mode where the wireless device determines when the        second wireless device is capable of transmitting a SID frame        using an extended time period, e.g., a time period that exceeds        eight speech frames.    -   Step 652: Is a SILENCE state detected? If yes, proceed to step        653. If no, the method ends.    -   Step 653: Measure one or more characteristics of a first speech        frame received by the UE 102.    -   Step 654: Compute one or more CN parameters based on the        measured one or more characteristics of the first speech frame.        For an AMR codec, the CN parameters can be based on a set of        weighted, averaged LSF parameter vectors and a set of averaged        logarithmic frame energy parameters. For an AMR-WB codec, the CN        parameters can be based on a set of weighted, averaged ISF        parameter vectors and a set of averaged logarithmic frame energy        parameters.    -   Step 655: Determine a weighted average of CN parameters of the        most recent extended sequence of N*8 speech frames (first        sequence), where the first speech frame is the most recent frame        in the first sequence.    -   Step 656: Store the weighted average of CN parameters for the        first sequence of frames.    -   Step 657: Does the weighted average of CN parameters of the        first sequence of speech frames exceed a parameter threshold? If        yes, proceed to step 664, if no, proceed to step 658.    -   Step 658: Retrieve from storage a weighted average of CN        parameters of a second extended sequence of N*8 speech frames        (second sequence), where the second speech frame is the most        recent speech frame in the second sequence.    -   Step 659: Determine a difference between the weighted average of        CN parameters of the most recent extended sequence of N*8 speech        frames (first sequence) and the weighted average of the CN        parameters of the previous extended sequence of N*8 speech        frames (second sequence)    -   Step 660: Does the difference between the CN weighted average of        most recent extended sequence of N*8 speech frames (first        sequence) and the CN weighted average of the previous extended        sequence of N*8 speech frames (second sequence) exceed a        difference threshold? If yes, proceed to step 664, if no,        proceed to step 661.    -   Step 661: Since entering the Silence state, has a SID_UPDATE        frame been transmitted? If yes, proceed to step 663. If no,        proceed to step 662.    -   Step 662: Does the time since entering the Silence state exceed        a first time threshold? If yes, proceed to step 664. If no,        proceed to step 665.    -   Step 663: Does the time elapsed since transmitting the most        recent SID_UPDATE exceed a second time threshold? If yes,        proceed to step 664. If no, proceed to step 665.    -   Step 664: Transmit a SID_UPDATE frame to the second wireless        device.    -   Step 665—Do not transmit a SID_UPDATE frame to the second        wireless device.        In some embodiments, steps 657 and 661-663 can be optional        steps. In some embodiments, one or more of the conditional tests        illustrated in steps 657, 660, and 661-663 can be used alone or        in combination to determine whether to send a SID_UPDATE frame.        Thus, the method illustrated can include one or more tests for a        parameter threshold, a difference threshold, and/or time        thresholds.

In some embodiments, step 659 is executed as follows: For an AMR codec,the SID_UPDATE frame is not transmitted to the receiving endpoint devicewhen a difference between the weighted average of the CN parameters,which include the LSF parameter vectors, for the first and secondsequences is less than an LSF threshold. Conversely, when the differencebetween the weighted average of the CN parameters, which include the LSFparameter vectors, for the first and second sequences equals or exceedsthe LSF threshold, the SID_UPDATE frame is transmitted. Similarly, foran AMR-WB codec, the SID_UPDATE frame is not transmitted to thereceiving endpoint device when a difference between the weighted averageof the CN parameters, which include the ISF parameter vectors, for thefirst and second sequences is less than an ISF threshold. Conversely,when the difference between the weighted average of the CN parameters,which include the ISF parameter vectors, for the first and secondsequences equals or exceeds the ISF threshold, the SID_UPDATE frame istransmitted. In some embodiments, a comparison of logarithmic frameenergy parameters can be used in place of or in addition to LSF/ISFparameter vectors to determine whether to send the SID_UPDATE frame tothe receiving endpoint device, e.g., by comparing logarithmic frameenergy parameter values (or averaged values) to an energy threshold.

FIG. 7 illustrates a block diagram of an apparatus 700 that can beimplemented on UE 102, in accordance with some embodiments. Theapparatus 700 of FIG. 7 can be configured to provide power optimizationfor the UE 102 using a VoLTE service while operating in a discontinuoustransmission (DTX) mode, in accordance with one or more embodiments. Itwill be appreciated that the components, devices or elements illustratedin and described with respect to FIG. 7 may not be mandatory and thussome may be omitted in certain embodiments. Additionally, someembodiments can include further or different components, devices orelements beyond those illustrated in and described with respect to FIG.7.

The apparatus 700 can include processing circuitry 706 that isconfigurable to perform actions in accordance with one or moreembodiments disclosed herein. In this regard, the processing circuitry706 can be configured to perform and/or control performance of one ormore functionalities of the apparatus 700 in accordance with variousembodiments, and thus can provide means for performing functionalitiesof the apparatus 700 in accordance with various embodiments. Theprocessing circuitry 706 can be configured to perform data processing,application execution and/or other processing and management servicesaccording to one or more embodiments.

In some embodiments, the apparatus 700 or a portion(s) or component(s)thereof, such as the processing circuitry 706, can include one or morechipsets, which can each include one or more chips. The processingcircuitry 706 and/or one or more further components of the apparatus 700can therefore, in some instances, be configured to implement anembodiment on a chipset comprising one or more chips. In some exampleembodiments in which one or more components of the apparatus 700 areembodied as a chipset, the chipset can be capable of enabling acomputing device, e.g., UE 102, to operate in the LTE wireless network100 when implemented on or otherwise operably coupled to the computingdevice, e.g., UE 102. Thus, for example, one or more components of theapparatus 700 can provide a chipset configured to enable a computingdevice to communicate using one or more cellular wireless technologies.In some embodiments, the processing circuitry 706 can include aprocessor 702 and, in some embodiments, such as that illustrated in FIG.7, can further include memory 704. The processing circuitry 706 can bein communication with or otherwise control wireless circuitry 710 and/ora power management module 708.

The processor 702 can be embodied in a variety of forms. For example,the processor 702 can be embodied as various processing hardware-basedmeans such as a microprocessor, a coprocessor, a controller or variousother computing or processing devices including integrated circuits suchas, for example, an ASIC (application specific integrated circuit), anFPGA (field programmable gate array), some combination thereof, or thelike. Although illustrated as a single processor, it will be appreciatedthat the processor 702 can comprise a plurality of processors. Theplurality of processors can be in operative communication with eachother and can be collectively configured to perform one or morefunctionalities of the apparatus 700 as described herein. In someembodiments, the processor 702 can be configured to execute instructionsthat can be stored in the memory 704 or that can be otherwise accessibleto the processor 702. As such, whether configured by hardware or by acombination of hardware and software, the processor 702 can be capableof performing operations according to various embodiments whileconfigured accordingly.

In some embodiments, the memory 704 can include one or more memorydevices. Memory 704 can include fixed and/or removable memory (or otherstorage) devices. In some embodiments, the memory 704 can provide anon-transitory computer-readable storage medium that can store computerprogram instructions that can be executed by the processor 702. In thisregard, the memory 704 can be configured to store information, data,applications, instructions and/or the like for enabling the apparatus700 to carry out various functions in accordance with one or moreexample embodiments. In some embodiments, the memory 704 can be incommunication with one or more of the processor 702, wireless circuitry710, or power management module 708 via one or more busses for passinginformation among components of the apparatus 700.

The apparatus 700 can further include wireless circuitry 710. Thewireless circuitry 710 can be configured to enable the apparatus 700 tosend wireless signals to and receive signals in accordance with one ormore wireless networking technologies. As such, the wireless circuitry710 can enable the apparatus 700 to send signals to and receive signalsfrom an eNodeB 110 (or an equivalent) of a wireless network, e.g., LTEwireless network 100. In some embodiments, the wireless circuitry 710includes hardware and/or software modules to perform operations toconvert digital data to and/or from analog wireless radio frequencywaveforms.

The apparatus 700 can further include power management module 708. Thepower management module 708 can be embodied as various means, such ascircuitry, hardware, a computer program product comprising computerreadable program instructions stored on a computer readable medium (forexample, the memory 704) and executed by a processing device (forexample, the processor 702), or some combination thereof. In someembodiments, the processor 702 (or the processing circuitry 706) caninclude, or otherwise control the power management module 708. The powermanagement module 708 can be configured to perform and/or otherwisecontrol power management in accordance with one or more embodimentsdisclosed herein. For example, power management module 708 can beconfigured to measure CN characteristics, determine weighted averages ofthe measured CN characteristics, and adjust SID frame transmission tomanage power consumption by a wireless device, e.g., the UE 102. A CNparameter computation can include an evaluation algorithm that can beused to determine as set of unquantized Linear Prediction (LP)parameters, e.g., using an ISF or LSF representation.

In some embodiments, a wireless communication device configured tomanage power consumption in a discontinuous transmission (DTX) mode incommunication with a Long Term Evolution (LTE) network includes wirelesscircuitry 710 configured to transmit frames to and receive frames from awireless network; power management module 708 coupled to processingcircuitry 706, where the power management module 708 is configured todetect voice inactivity and to measure one or more characteristics of afirst frame received by the wireless communication device; and theprocessing circuitry 706 coupled with the wireless circuitry 710,wherein the processing circuitry 706 is configured to:

-   -   generate one or more CN parameters based on the measured one or        more characteristics of the first frame;    -   determine a weighted average of CN parameters for a first        sequence of frames, where the first sequence of frames is the        most recent sequence of frames and the first frame is the most        recent frame in the first sequence of frames;    -   store the weighted average of CN parameters for the first        sequence of frames in a memory 704 (or in other suitable        storage);    -   retrieve from memory 704 (or from other suitable storage) a        weighted average of CN parameters for a second sequence of        frames, wherein the weighted average of CN parameters of the        second sequence of frames is based on a sequence where the        second frame is most recent frame in the second sequence of        frames;    -   determine when the difference between the weighted average of CN        parameters of the first sequence of frames and the weighted        average of CN parameters of the second sequence of frames        exceeds a difference threshold; and    -   transmit one or more silence descriptor update (SID_UPDATE)        frames when the difference between the weighted average of CN        parameters of the first sequence of frames and the weighted        average of CN parameters of the second sequence of frames        exceeds the difference threshold.

The aforementioned methods can be implemented at a wirelesscommunication device, e.g., the UE 102. In an embodiment, the UE 102determines when voice inactivity occurs, e.g., a SILENCE state. Whenvoice inactivity occurs, the UE 102 measures characteristics of thefirst frame received. For an AMR codec, the characteristics can includea set of LSF parameter vectors and a set of logarithmic frame energyparameters. For an AMR-WB codec, the characteristics can include a setof ISF parameter vectors and a set of logarithmic frame energyparameters. Using the measured characteristics of the first frame, theUE 102 can generate CN parameters and determine a weighted average ofcomfort noise parameters of the first sequence, when a first sequence offrames is the most recent sequence of frames and the first frame is themost recent frame in the first sequence of frames. The UE 102 determinesa difference between the weighted average of the CN parameters of thefirst sequence of frames and a weighted average of the CN parameters ofthe second sequence of frames. When the difference between the weightedaverages exceeds a difference threshold, the UE 102 sends a SID frame toa second wireless device to notify the second wireless device of thevoice inactivity. After sending the SID frame, the UE 102 powers downall or portions of a transmitter to conserve power. The method allowsthe UE 102 to control timing for the transmission of SID frames, ascompared with current LTE wireless communication protocols. Theaveraging period can be adjusted from a fixed length of eight frames toa length of N*8 frames, where N is an integer greater than one and isdetermined at least in part by the CN parameters. In some embodiments,the value for N is adapted over time based on the CN parameters. Themethods described herein allow the UE 102 to optimize power consumptionwhile maintaining voice quality.

The embodiments described herein relate to methods and apparatus forpower saving for LTE wireless networks while using VoLTE serviceoperating in a DTX mode. Multiple LTE specifications have been developedand ratified by the 3GPP. Generally, the term “LTE” refers to 3GPPReleases 8 and 9 and the term “LTE Advanced” refers to 3GPP Releases 10to 13. LTE and LTE Advanced can be referred to as the 4^(th) generationmobile networks (4G). Beyond 4G, 3GPP can continue to develop newspecifications with future releases referred to as 5^(th) generationmobile networks (5G). The specifications for the 5G mobile networks areexpected to support packet-based voice and data communications. Oneskilled in the art can recognize that the described embodiments can beapplied to wireless networks that use packet-based voice transmissionwith silence detection, such as under development for 5G wirelesssystems, and are not limited solely to 4G/LTE/VoLTE wireless systems.Any wireless system that uses packet-based voice with silence detectionand silence update frames can benefit from the methods, apparatuses, andsystems described herein.

The foregoing description, for purposes of explanation, used specificnomenclature to provide a thorough understanding of the describedembodiments. However, it will be apparent to one skilled in the art thatthe specific details are not required in order to practice the describedembodiments. Thus, the foregoing descriptions of the specificembodiments described herein are presented for purposes of illustrationand description. They are not target to be exhaustive or to limit theembodiments to the precise forms disclosed. It will be apparent to oneof ordinary skill in the art that many modifications and variations arepossible in view of the above teachings.

What is claimed is:
 1. A method for reducing power consumption of a userequipment (UE), the method comprising: at the UE while operating in adiscontinuous transmission (DTX) mode in communication with a second UEvia a Long Term Evolution (LTE) wireless network: detecting a period ofvoice inactivity; measuring one or more characteristics of a firstspeech frame; computing one or more comfort noise parameters based onthe measured characteristics of the first speech frame; determining aweighted average of comfort noise parameters of a first sequence ofspeech frames, the first sequence including the first speech frame as amost recent speech frame; determining a difference between the weightedaverage of the comfort noise parameters of the first sequence of speechframes and a weighted average of comfort noise parameters of a secondprevious sequence of speech frames, the second previous sequenceincluding a second speech frame different from and earlier than thefirst speech frame as a most recent speech frame; and transmitting oneor more silence descriptor update (SID_UPDATE) frames to the second UEvia the LTE wireless network when the difference between the weightedaverage of the comfort noise parameters of the first sequence of speechframes and the weighted average of the comfort noise parameters of thesecond sequence of speech frames exceeds a difference threshold, whereinthe first sequence of speech frames and the second sequence of speechframes each (a) span an identical number of consecutive speech frames,(b) overlap by at least one speech frame, and (c) are offset by at leastone speech frame.
 2. The method as recited in claim 1, furthercomprising withholding transmission of SID_UPDATE frames to the secondUE when the difference between the weighted average of the comfort noiseparameters of the first sequence of speech frames and the weightedaverage of the comfort noise parameters of the second sequence of speechframes does not exceed the difference threshold.
 3. The method asrecited in claim 1, further comprising: storing the weighted average ofthe comfort noise parameters of the first sequence of speech frames; andretrieving from storage the weighted average of the comfort noiseparameters of the second sequence of speech frames.
 4. The method asrecited in claim 1, further comprising transmitting the one or moreSID_UPDATE frames to the second UE via the LTE wireless network, whenthe weighted average of the comfort noise parameters of the firstsequence of speech frames exceeds a parameter threshold.
 5. The methodas recited in claim 1, further comprising: after entering a SILENCEstate, transmitting to the second UE via the LTE wireless network atleast one SID_UPDATE frame, when no SID_UPDATE frame has beentransmitted and a time elapsed since entering the SILENCE state exceedsa first time threshold.
 6. The method as recited in claim 1, furthercomprising: after entering a SILENCE state, transmitting to the secondUE via the LTE wireless network at least one SID_UPDATE frame, when afirst SID_UPDATE frame has been transmitted and a time elapsed sincetransmitting a most recent SID_UPDATE frame while in the SILENCE stateexceeds a second time threshold.
 7. The method as recited in claim 1,wherein a time interval between successive transmitted SID_UPDATE framesequals or exceeds the number of consecutive speech frames in the firstsequence of speech frames.
 8. A wireless communication devicecomprising: wireless circuitry configured to communicate with a wirelessnetwork; a power management module communicatively coupled to processingcircuitry, wherein the power management module is configured to detectvoice inactivity and measure characteristics of speech frames includinga first speech frame; and the processing circuitry communicativelycoupled to the wireless circuitry, wherein the processing circuitry isconfigured to cause the wireless communication device to: generatecomfort noise parameters based on measured characteristics of speechframes including the first speech frame; determine a weighted average ofthe comfort noise parameters of a first sequence of speech frames, thefirst sequence including the first speech frame as a most recent speechframe; determine a difference between the weighted average of thecomfort noise parameters of the first sequence of speech frames and aweighted average of comfort noise parameters of a second sequence ofspeech frames, the second sequence including a second speech framedifferent from and earlier than the first speech frame; and transmit oneor more silence descriptor update (SID_UPDATE) frames to a secondwireless communication device via the wireless network when thedifference between the weighted average of the comfort noise parametersof the first sequence of speech frames and the weighted average of thecomfort noise parameters of the second sequence of speech frames exceedsa difference threshold, wherein the first sequence of speech frames andthe second sequence of speech frames each (a) span an identical numberof consecutive speech frames, (b) overlap by at least one speech frame,and (c) are offset by at least one speech frame.
 9. The wirelesscommunication device as recited in claim 8, wherein the processingcircuitry is further configured to: store the weighted average of thecomfort noise parameters of the first sequence of speech frames in amemory; and retrieve from memory the weighted average of the comfortnoise parameters of the second sequence of speech frames.
 10. Thewireless communication device as recited in claim 8, wherein the comfortnoise parameters comprise a set of immittance spectral frequency (ISF)parameter vectors and/or a set of logarithmic frame energy parameters.11. The wireless communication device as recited in claim 8, wherein thecomfort noise parameters comprise a set of line spectral frequency (LSF)parameter vectors and/or a set of logarithmic frame energy parameters.12. The wireless communication device as recited in claim 8, wherein theprocessing circuitry is further configured to: transmit one or moreSID_UPDATE frames to the second wireless communication device via thewireless network, when the weighted average of the comfort noiseparameters of the first sequence of speech frames exceeds a parameterthreshold.
 13. A non-transitory computer readable storage medium storingcomputer program code that, when executed by one or more processorsimplemented on a user equipment (UE) operating in a discontinuoustransmission (DTX) mode in communication with a second UE via a wirelessnetwork, causes the UE to perform a method comprising: in response todetecting a period of voice inactivity: measuring characteristics of afirst speech frame; generating comfort noise parameters based on themeasured characteristics of the first speech frame; determining aweighted average of the comfort noise parameters of a first sequence ofspeech frames, the first sequence including the first speech frame as amost recent speech frame; determining a difference between the weightedaverage of the comfort noise parameters of the first sequence of speechframes and a weighted average of comfort noise parameters of a secondsequence of speech frames, the second sequence including a second speechframe different from and earlier than the first speech frame; andtransmitting one or more silence descriptor update (SID_UPDATE) framesto the second UE when the difference between the weighted average of thecomfort noise parameters of the first sequence of speech frames and theweighted average of the comfort noise parameters of the second sequenceof speech frames exceeds a difference threshold, wherein: the firstsequence of speech frames comprises a first set of N*8 most recentspeech frames, where N is an integer greater than one, the secondsequence of speech frames comprises a second set of N*8 speech framesthat overlaps and is offset from the first set by at least one speechframe, and each SID_UPDATE frame is spaced apart by a time period thatexceeds a time span of eight successive speech frames.
 14. Thenon-transitory computer readable storage medium as recited in claim 13,wherein the comfort noise parameters comprise a set of immittancespectral frequency (ISF) parameter vectors and/or a set of logarithmicframe energy parameters.
 15. The non-transitory computer readablestorage medium as recited in claim 13, wherein the comfort noiseparameters comprise a set of line spectral frequency (LSF) parametervectors and/or a set of logarithmic frame energy parameters.
 16. Thenon-transitory computer readable storage medium as recited in claim 13,wherein the integer N varies based on the comfort noise parameters. 17.The non-transitory computer readable storage medium as recited in claim13, wherein the time period separating successively transmittedSID_UPDATE frames equals a time period of N*8 successive speech frames.18. The non-transitory computer readable storage medium as recited inclaim 13, wherein the time period separating successively transmittedSID_UPDATE frames varies over time based on the comfort noiseparameters.
 19. The method of claim 1, wherein a time interval betweensuccessive SID_UPDATE frames equals or exceeds a time span of eightsuccessive speech frames.
 20. The non-transitory computer readablestorage medium as recited in claim 13, wherein the method performed bythe UE further comprises: transmitting one or more SID_UPDATE frames tothe second UE via the wireless network, when the weighted average of thecomfort noise parameters of the first sequence of speech frames exceedsa parameter threshold.